In this work, we present measurements of efficiency-optimized 940 nm diode laser bars with long resonators that are
constructed with robustly passivated output facets at the Ferdinand-Braun-Institut (FBH). The measurements were
performed at room temperature on a test bench developed at HiLASE Centre, as a function of operating condition. The
single-diode bars generated < 1.0 kW when tested with 1 ms pulses at 1-10Hz operating frequency, corresponding to < 1
J per pulse. The maximum electrical-to-optical efficiency was < 60 %, with operating efficiency at 1 kW of < 50%,
limited by the ~ 200 μΩ resistance of the bar packaging. In addition, slow axis divergence at 1 kW was below 6° FWHM
and spectral width at 1 kW was below 7 nm FWHM, as needed for pumping Yb-doped solid state amplifier crystals.